I think its definitely a cult classic, not necessarily because the show itself is popular, but the idea is. It's one of those anime that everyone (as in all anime fans) recognizes, but when I talk to people about it irl, most often it was either something they watched as a kid, or something they haven't actually watched, but know about. And definitely most of the new media is intended for adult audiences rather than children, with the more serious tones in Crystal and the Nelke musicals, other events like the classical concert, and even merch being more mature, with lots of clothes and makeup intended for actual, serious wearing. Of course, there are exceptions like the USJ ride which is fun for all ages, and the recent novelization of the manga for children, but as a whole, the current Sailor Moon is one focused on garnering nostalgia in old fans, rather than forming new ones. Though most of that stuff is in Japan, and has less to do with the status of Sailor Moon in the English speaking world...
And for that reason, I don't think Sailor Moon will ever really be as popular as Star Wars or Star Trek. It's one of the largest and most recognizable anime, possibly the most recognizable shoujo, but I think it will always be seen as a part of the category of "anime" rather than regarded on its own. It's things like this that make me wonder what a world would be like where Saban Moon had actually aired, and just how much the English and Japanese Sailor Moon communities would differ...